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Access 5.x |
Dehumidification |
Access allows override control of the selected sequence (typically the cooling sequence) to enable dehumidification of the supply air through condensation. During this mode, the dehumidification function overrides the cooling signal from the temperature controller, allowing the output to activate even when there is no cooling demand. The dehumidification output increases as the room or extract-air humidity rises.
Starting from Access version 5.4, the dehumidification function has been enhanced with a dew-point control feature. When enabled, dehumidification will only activate if the dew point can be reached. To enable dew-point calculation and control, three new configuration parameters have been introduced:
- Cooler capacity (kW)
- Cooler inlet air temperature
- Cooler inlet air humidity
To reheat the dehumidified (dried) air, the reheater is used. However, in some cases, reheating alone may not be sufficient, and the supply-air temperature may drop below acceptable limits. To prevent this, a compensation algorithm can be activated. When the after-heater operates at maximum capacity, this algorithm allows the temperature controller to counteract the humidity controller by reducing the dehumidification demand, thus maintaining an acceptable supply-air temperature.
To enable this compensation control, the Humidity Setpoint Compensation sequence must be activated.
Configuration example of the dehumidification (sequence "SEQ-C Cooling") |
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Variable |
Available options & Selection |
Note |
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Activate Humidity control |
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Configuration > Functions > Function activation |
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Humidity control |
... | Dehumidification |… |
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Configure function |
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Configuration > Functions > Humidity control |
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Humidity control |
Dehumidification |
Indication of what function has been activated |
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Select sequence for dehumidify |
... | Cooling |... |
Sequence to be used for dehumidification |
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Block dehumidification when dew point not reached |
| No | Yes | |
Default | No| The settings bellow are only available if selected | Yes | |
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Capacity of cooler |
[0] kW |
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Cooler inlet air temperature |
| Cooler inlet air temperature | Efficiency temperature exchanger | Outdoor temperature | |
Choose sensors to measure temperature and humidity of the air entering the cooling coil |
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Cooler inlet air humidity |
| Cooler inlet air humidity | Humidity outdoor | |
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PID Settings |
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Configuration > PID controllers > Dehumidification |
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P-band |
[100] %RH |
PID settings for dehumidification signal |
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I-time |
[300] s |
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D-time |
[0] s |
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PID output max limit |
[100] % |
max output of the PID can be limited |
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Hardwired interface |
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Configuration > I/O allocation settings > Analog inputs > |
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Humidity room/extract air |
Any available I/O |
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Cooler inlet air temperature |
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Cooler inlet air humidity |
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Operational settings |
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Data & Settings > Humidity control |
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Humidity room/extract air |
__ % |
Actual measured RH |
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Setpoint humidity room/extract |
[50] %RH |
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Operation overview |
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Data & Settings > Operation overview > Humidity |
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Humidity room/extract air |
__ % |
Overview of the function in action |
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Setpoint humidity room/extract |
[50] %RH |
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Humidity control |
__ % |
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Humidity control mode |
Not active | Dehumidification |
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Calculated lowest temperature - cooling capacity |
__oC |
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Dewpoint cooler - start condensation |
__oC |
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Cooler inlet air temperature |
__oC |
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Cooler inlet air humidity |
__ %RH |
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Data & Settings > Operation overview > Cooling |
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Cooling (SEQ-C) |
__ % |
Overview of the performance of the sequence |
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Cooling start (SEQ-C) |
Off | On |
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Cooling pump (SEQ-C) |
Off | On |
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